Are silicones toxic?

While the research indicates that silicones are certainly very stable, they are not completely inert. In other words, there is a possibility of leaching. For example, one study tested the release of siloxanes from silicone nipples and bakeware into milk, baby formula, and a solution of alcohol and water. Nothing was released into the milk or formula after six hours, but after 72 hours in the alcohol solution, several siloxanes were detected. Siloxanes are considered potential endocrine disrupters, and some have been linked to cancers.

Many experts and authorities consider silicones to be nontoxic and safe for contact with food and drink. For example, Health Canada states: "There are no known health hazards associated with use of silicone cookware. Silicone rubber does not react with food or beverages, or produce any hazardous fumes."

While the scientific evidence is weak in pointing a smoking gun at silicones, the questions and uncertainty are there, so it’s worth keeping a close eye on them—especially given the growing concerns about endocrine-disrupting chemicals. Siloxanes are also present at detectable levels in land, air, and water, and given their durability, they tend to persist in the environment for a long time.